Apparatus capable of use as a pump or a motor

ABSTRACT

There is disclosed hereinafter an apparatus which may be used as a pump, particularly suitable for fuel injection, or as a fluid driven motor. The apparatus comprises at least one flexible diaphragm which defines with a supporting part thereof a chamber for receiving fluid, and a compression element which is operatively connected to a rotary shaft and moves with an oscillatory action normal to the diaphragm, and bears on the diaphragm, to compress the chamber intermittently so that fluid in the chamber in pressurized and leaves the chamber with a pulse-like action.

United States Patent 1151 3,687,580

Griffiths Aug. 29, 1972 54 APPARATUS CAPABLE OF USE AS A 3,502,0343/1970 Pickup ..417/477 x PUMP OR A MOTOR 2,332,157 10/1943 Mapson..4l8/45 2,679,807 6/1954 Bruckmann ..4l8/45 [72] Inventor Kennethwalsan England 2,414,355 1/1947 B6 6s16ws1 ..418/45 [73] Assignee:Griffiths Fuel Injection (Development) Limited, T ll, s k FOREIGNPATENTS OR APPLICATIONS Trent England 1,228,534 3/1960 France ..4l8/45[22] Filed: May 26, 1970 Primary Examiner-William L. Freeh [21] Appl'40543 Assistant Examiner-Richard E. Gluck Att0meyl(em0n, Palmer &Estabrook [30] Foreign Application Priority Data May 31, 1969 GreatBritain ..27,685/69 [571 ABSTRACT June 1969 Great Britain --32,556/69There is disclosed hereinafter an apparatus which may be used as a pump,particularly suitable for fuel injec- U-S. ..418/45, tion or as a drivenmotor The apparatus com- [51] I "Folc 0 F04b 43/08 F04b 43/12 prises atleast one flexible diaphragm which defines [58] Fleld of Search""418/45; 417/476 477; 92/132 with a supporting part thereof a chamberfor receiving fluid, and a compression element which is operatively [56]References cued connected to a rotary shaft and moves with an oscilla-UNITED STATES PATENTS tory action normal to the diaphragm, and bears onthe diaphragm, to compress the chamber mtermittently so 2711257 1/ 1883Morton "418/45 X that fluid in the chamber in pressurized and leaves the3,180,272 4/1965 Broadfoot ..4l8/477 X chamber with a pulse like action.3,216,362 11/1965 Hewko ..417/477 3,433,170 3/1969 Malbec ..417/477 X 9Claims, 8 Drawing Figures I 37 9 3 4 I j 33 47 1 I I 43 r r 25 II 4 7 1.x 71 77 J5 32 24 3O 37 23 PATENTEmuszs 1912 saw 2 or 4 m w 7 5 W 7 5 2APPARATUS CAPABLE OF USE AS A PUMP OR A MOTOR This invention relates toapparatus capable of use as a pump for imparting energy to fluids, or asa fluiddriven motor.

An object of the present invention is to provide apparatus capable ofuse as a pump or a motor comprising at least one flexible diaphragmwhich defines with a diaphragm-supporting part a chamber for receivingfluid, and compressing means operable connected to a rotary shaft andmovable with substantially oscillatory action normal to the diaphragm soas to bear on the diaphragm to compress the chamber intermittently andthereby cause fluid supplied to the chamber in use to be pressurized inthe chamber.

The apparatus may be used with gaseous and liquid fluids. Where theapparatus is used as a pump fluid will normally be supplied continuallyto the chamber at a predetermined pressure. The intermittent compressingof the chamber by the compression means causes the fluid to bepressurized in the chamber and to be propelled out of the chamber underpressure with a pulse-like action. There may be just one diaphragm, andhence just one chamber, or there may be a plurality of diaphragms. Whenthe apparatus is used as a pump, the rotary shaft operates thecompressing means. Where the apparatus is used as a motor it willusually be necessary to have at least two diaphragms and hence twochambers, which are successively operated upon by the compression means,in order to avoid dead spots in the operation of the motor. Fluid issupplied continually to each chamber under pressure and the build up ofpressure in the chamber due to compression of the chamber by thecompression means causes movement of the compression means which istransferred to the rotary shaft to rotate the shaft. The fluid againleaves the chamber with a pulse-like action.

Normally the chamber defined by the diaphragm and supporting part willbe elongated, with fluid being supplied to the chamber near one end, andleaving the chamber at or near its opposite end. The chamber thusdefined extends arcuately about, and usually substantiallyconcentrically with, 'the axis of the rotary shaft. The chamber maytaper towards one end.

The diaphragm may be a separate flexible membrane member secured andsealed to the supporting part. In such an arrangement the diaphragm maybe of suitable rubber, synthetic rubber, plastics material or evenpossibly of metal having the required flexibility. It is preferred,however, because sealing problems are then avoided, that the diaphragmis formed integrally with the supporting part. It may for example beformed by a wall, or part of a wall, of a flexible tubular member, theremainder of which member constitutes the supporting part for thediaphragm. A tubular member may be provided in which the diaphragm isformed by a thinwalled, hollow, elongated, protruberance on one surfaceof a pad of flexible material which forms the supporting part, theinterior of the protruberance forming the chamber for the fluid. Aflexible, preferably strong, wear-resistant plastics material issuitable for the tubular member, although rubber and synthetic rubbermay possibly be used as alternative materials, provided that they havesufficient strength and resistance to wear. The diaphragm-forming partof the tubular member is on the inner circumferential side of thetubular member. Fluid inlet and outlet passages leading respectively toand from the chamber open to the outer circumferential side of thetubular member through the supporting part where connection is made tofluid supply and discharge pipes. The tubular member has sealed ends,and the inlet and outlet passages are provided near the ends.

It is preferred that the supporting part, whether it is formed.integrally with the diaphragm or not, is flexible in order that it willabsorb some of the shock loads resulting from the compressingengagements of the compression means with the diaphragm, which mightotherwise cause choking of fluid in the chamber.

It is an essential requirement of the apparatus in accordance with thepresent invention that the compression means bears on the diaphragm tocompress the chamber by movement of the compression means nor mal to thediaphragm. Hence there is no rolling or sliding contact between thecompression means and the diaphragm, and therefore there is little or nofriction between them so that wear on the diaphragm is minimized.

The compression means may comprise a disc or annulus which is mounted onbut restrained from rotation with an eccentric rotatable with the rotaryshaft, so that, because of the eccentric, the disc or annulus movesrelative to the axis of the shaft with an oscillatory action and itsperiphery progressively describes a circle of larger diameter than thatof the disc or annulus, and as it does so it bears on the diaphragmcausing the chamber to be progressively compressed from its inlet end toits outlet end, with the result that fluid in the chamber is forced toflow along the chamber to the outlet. In the case of the apparatus beingused as a pump the pressure of the fluid increases as it is forced toflow along the chamber. It will be appreciated that although the chamberis progressively compressed from its inlet end to its outlet end, thisis effected by the discs bearing on the diaphragm to apply pressure onlyin a direction substantially normal to the surface of the diaphragm, andnot by a rolling action. Where there is more than one diaphragm they maybe disposed at angularly spaced intervals around a single disc orannulus which bears on the diaphragms in turn to compress theirassociated chambers, or alternatively there may be two or more discs orannuli each of which is arranged to co-operate with one or morediaphragms.

If desired, means may be provided for varying the extent by which fluidin the chamber will be pressurized.

There are various uses to which the apparatus may be put. Oneapplication for which the apparatus when used as a pump is particularlysuitable is for fuel injection in motor vehicles. It may be applied tosingle and multi-cylinder engines.

Embodiments of apparatus in accordance with the invention which take theform of fuel injection pumps for single cylinder internal combustionengines, will now be described by way of example with reference to theaccompanying drawings in which:

FIG. 1 is a cross-section through one form of fuel injection pump,

FIG. 2 is a partly exploded axial section through the pump taken on line2-2 of FIG. 1,

FIG. 3 is a cross-section through a further form'of fuel injection pumpwhich is adjustable,

FIG. 4 is a cross-section through another adjustable form of fuelinjection pump,

FIG. 5 is a small partly sectioned front view of a modified form ofintegral diaphragm and support part which may be used in the pump shownin FIGS. 1 and FIG. 6 is a partly sectioned perspective view of amodified form of integral diaphragm and support part which may be usedin the pump shown in FIG. 3 or FIG.

FIG. 7 is a cross-section through a modified form of the fuel injectionpump shown in FIGS. 1 and 2 of the accompanying drawings, and

FIG. 8 is a further modified form of the pump shown in FIGS. 1 and 2.

The fuel injection pump shown in FIGS. l and 2 of the accompanyingdrawings has a cylindrical housing 10 having a peripheral wall 1 1 andan annular back wall 12 formed with a central, rearwardly-directed,axial sleeve portion 13. A circular cover plate 14, which seats at itsperiphery on the forward edge of the peripheral wall 1 l, closes thefront of the housing 10.

In the sleeve 13 is a bearing 15 in which is journalled a shaft portion16 of an eccentric 17 disposed in the housing 10. In this instance thesleeve 13 is arranged to be received into a socket 18 of complementarydiameter formed in a casing 19, FIG. 2, of an internal combustionengine. When the sleeve 13 is received into the socket 18 the rear faceof the back wall 12 of the housing 10 lies flush against the enginecasing 19. At its outer end 20 the shaft 16 of the eccentric 17 issquared and engages in a complementary socket 21 in the end of a driveshaft 22 which may for example be driven by the cam-shaft drive of theengine, or by the crank shaft drive, or any other suitable part of theengine.

Fitted to the eccentric 17 within the housing 10 is a bearing 23 onwhich is centrally mounted a metal disc 24 of somewhat smaller diameterthan the internal diameter of the peripheral wall 1 l of the housing. Inthe periphery of the disc 24 there is a notch 25 of elongatedrectangular shape which extends radially of the disc. Engaged in thisnotch 25 is a square-section block 26 having co-axial journals 27 at itsopposite ends which are received into bearing sockets 27' and 27" in theback wall 12 of the housing 10 and the inner plate 14 respectively. Theblock 26 and its journals 27 may be formed as a moulding in a suitableplastics material having self-lubricating qualities. The width of thenotch 25 is only slightly larger than that of the block 26 but the depthof the notch 25, that is the dimension of the notch measured radially ofthe disc 24, is appreciably greater than the dimension of the block 26measured in the same direction. The engagement of the block 26 in thenotch 25 restrains the disc 24 from rotating with the eccentric 17, andhence with the drive shaft 22, but allows the disc to move relative tothe axis of the shaft under the action of the eccentric so that theperiphery of the disc progressively describes a circle of largerdiameter than that of the disc.

Inside the housing 10 a tubular member 28 is secured against theinternal surface of the peripheral wall 11. The tubular member 28extends arcuately through approximately 300 along the peripheral wall 11and the radially innermost surface of the tubular member lies on acircle of diameter approximately equal to the diameter of the disc. Thetubular member 28 is of regular oval cross-section with sealed ends 29,and it forms a composite diaphragm 30 and support 31 for the diaphragm;the diaphragm 30 being formed by the radially innermost wall portion ofthe tubular member, and the support 31 being formed by the radiallyoutermost wall portion, the opposite side walls portions defining therounded ends of the oval cross-section of the tubular member, and thesealed ends 29 of the tubular member. The tubular member 28 is formedfrom flexible, strong, wear-resistant synthetic plastics material, suchas for example VIT ON (Trade Mark), which is moulded to shape. Theinterior of the tubular member 28 forms a closed chamber 32. The sealedends 29 of the tubular member 28 are disposed at the side of the housing10 nearest to the block 26 and they lie on opposite sides of, at equaldistances from, a notional line extending radially of the disc 24through the axis of the journals 27 of the block. Formed integrally withthe radially outermost wall portion of the tubular member 28 near toeach of the sealed ends 29 is a tubular spigot portion 33, 34 the boreof which opens into the chamber 32. The one spigot portion 33 providesan inlet to the chamber 32 and the other spigot portion 34 provides anoutlet from the chamber. The spigot portions 33 and 34 respectivelycommunicate with the bores of internally screw-threaded bosses 35 and 36formed on the exterior of the peripheral wall 11 of the housing 10.Connected to that boss 35 with the bore of which the inlet spigot 33communicates is a non-return valve 37 of known type and connected inturn to the non-return valve 37 is a fuel supply pipe 38. Connected tothe other boss 36, with the bore of which the outlet spigot 34communicates, is a normally closed pulsevalve 39, also of known type, towhich is connected a fuel discharge pipe 40 leading to a fuel controland injector, not shown.

The cover plate 14 is secured in place by means of screws 41 the shanksof which extend through plain, countersunk holes 42 in the cover plate,through holes 43 in the disc 24 and through plain holes 44 in the backwall 12 of the housing 10, and are screwed into tapped holes in theengine casing 19. The holes 43 in the disc 24 are sufficiently larger indiameter than the shanks of the screws 41 to allow for the movement ofthe disc with the eccentric 17 without interference from the screws.

In use fuel is continually supplied at a constant predetermined pressureto the chamber 32 by way of the fuel supply pipe 38, non-return valve 37and inlet spigot 33. Because of the action of the eccentric l7 rotatingwith the drive shaft 22, the periphery of the disc 24 engages with thediaphragm part 30 of the tubular member 28 and causes the chamber 32 tobe progressively compressed from its inlet end to its outlet end, withthe result that fluid in the chamber is forced to flow along the chamberto the outlet spigot 34. The pressure of the fluid in the chamberincreases as it is forced to flow along the chamber. The pressure of thefluid opens the pulse-valve 39 so that the fluid can pass out of thechamber, with a pulselike action, by way of the outlet spigot 34 and tothe discharge pipe 40. When the disc moves out of engagement with thediaphragm, and hence the chamber 32 is uncompressed and the fuel in thechamber returns to its normal, pre'determined, pressure, the pulse-valve39 closes.

The resilience of the tubular member absorbs some of the shock loadresulting from the compressing engagement of the disc 24 with thediaphragm part 30, and thereby avoids the possibility of fuel choking inthe chamber 32.

Instead of the tubular member 28 described and illustrated in FIGS. 1and 2, an annular pad 45 may be provided, as shown in FIG. 5, which ismoulded from flexible, strong, wear-resistant plastics material. Formedon the inner circumferential surface of the pad 45 is a thin-walled,hollow, protruberance 46 which extends along a substantial part of thecircumferential length of the inner surface of the pad. Thisprotruberance 46 constitutes a diaphragm and the pad constitutes anintegral support for the diaphragm. The interior of the protruberance 46forms a chamber 47. A fuel inlet 48 and a fuel outlet 49 openingrespectively into and from opposite ends of the chamber 47, extend fromthe outer circumferential surface of the pad 45 for connection to fuelsupply and discharge pipes respectively. The pad 45 need not necessarilybe a complete annulus.

In the embodiment shown in FIG. 3, the fuel injection pump again has ahousing which is of basically similar form to the housing 10 of the lastdescribed embodiment except that part of the peripheral wall 11 isremoved leaving an opening 50 at one side of the housing. Fitted in thisopening 50 is an arcuate shoe 51 an inner surface 52 of which forms ineffect a continuation of the inner surface of the peripheral wall of thehousing 10. The shoe 51 has an integral lug 53 near one end by which itis arranged to be pivoted to a suitable fixed mounting so that the shoecan be swung angularly about the pivot towards and away from the axis ofthe housing 10.

Secured on the inner surface 52 of the shoe 51 is an oblong, similarlyarcuately curved, moulded tubular member 54 which is generally similarto the tubular member 28 of the first described embodiment except thatit is shorter; the innermost wall portion of the tubular member forminga diaphragm 55 and the remainder of the member forming in effect asupport 56 for the diaphragm. This tubular member 54 also has sealedends 57, and, on its outer surface 58, a tubular inlet spigot 59 thebore of which opens to one end of a chamber 60 defined by the interiorof the tubular member 54, and a tubular outlet spigot 61 the bore ofwhich opens to the opposite end of the chamber 60. The inlet spigot 59communicates with the bore of an internally threaded boss 62 on theouter surface 58 of the shoe 51 at the end of the shoe remote from thelug 53, to which boss 62 on a non-return valve 63 is connected, to whichin turn a fuel supply pipe 64 is connected. The outlet spigot 61communicates with the bore of an internally threaded boss 65 at theopposite end of the shoe 51 to which boss a normally closed pulse-valve66 is connected. A fuel discharge pipe 67 is connected to thepulse-valve 66.

On the outer surface 58 of the shoe intermediate the lug 53 and the boss62 is a raised bearing surface 68 which is engaged by a cam 69 pivotedto a suitable fixed mounting, not shown, and which is convenientlycontrolled by an accelerator of the vehicle to which the pump is fittedin use. Actuation of the cam 69 causes the shoe to swing towards theaxis of the housing 10.

The shoe may normally be urged in the direction away from the axis ofthe housing by spring loading, not shown.

The rest of the pump shown in FIG. 3 is similar to the pump of the firstdescribed embodiment and the eccentric, disc and block are identified bythe same reference numerals as those used in the previous embodiment forthese parts. The disc 24 is operated as before.

Under the action of the eccentric 17 a portion of the periphery of thedisc 24 is caused to move into contact with the diaphragm 55 once inevery revolution of the eccentric. At low idling speeds of the enginethe peripheral portion of the disc 24 engages and presses on thediaphragm 55 only near the inlet end of the chamber 60 and causes justthat end portion of the chamber to be compressed. As the chamber 60 iscompressed fuel is forced from that end portion of the chamber into theremaining un-compressed portion of the chamber, with the result that thepressure of the fuel in the chamber is increased and the fuel is urgedto leave the chamber by way of the outlet spigot 61. The increasedpressure of the fuel opens the pulse valve 66 so that the fuel can passto the discharge pipe 67. When the disc 24 moves out of compressingengagement with the diaphragm 55 and the chamber returns to its normalstate so that the fuel return to its normal, pre-determined pressure,the pulse valve 66 closes. Upon turning the cam 69 so that the shoe 51is swung towards the disc the area of the diaphragm 55 which the discengages is increased, and therefore more of the chamber is caused to becompressed. This of course increases the pressure of the fuel in theun-compressed portion of the chamber and increases the velocity of theflow of the fuel out of the chamber.

In FIG. 4 an alternative arrangement is shown for varying the extent bywhich fuel in the chamber is pressurized. The fuel injection pump isgenerally similar to that illustrated by FIG. 3 of the drawings, and thecorresponding parts of the pump are identified by the same referencenumerals as those used in FIG. 3. The difference between the two formsof pump lies in the fact that in the arrangement of FIG. 4 the shoe 63is not pivotally movable but instead is linearly movable towards andaway from the disc 24. In this instance there are formed integrally onthe outer surface 58 of the shoe 63 two parallel, tubular bosses 70, onebeing positioned near to the inlet boss 62, and the other beingpositioned near to the outlet boss 65. These tubular bosses 70 areengaged by fixing pegs 71. The bosses 70 are slidable along the pegs 71.A cam, not shown, such as the cam 69 in the last described embodiment,may act on the outer surface 58 to cause the shoe, and hence thediaphragm part 55 of the tubular member 54, to be moved linearly of thepegs 71 towards and away from the disc 24 to vary the area of thediaphragm which is engaged by the disc and thereby vary the extent bywhich the chamber 60 is compressed so as to alter the pressure of thefuel as required. The movement of the shoe 63 relative to the pegs 71may be effected in other convenient ways, as will be appreciated. Again,the shoe 63 may normally be spring-loaded away from the disc 24.

Instead of the tubular member 54 provided in the pumps illustrated byFIGS. 3 and 4, an arcuate pad 72, as shown in FIG. 6, may be used. Thepad 72 is moulded from flexible, strong, wear-resistant plasticsmaterial, such as for example VITON (Trade Mark). It has formed on itsinner surface a thin-walled, hollow, protruberance 73 which extendsalmost the full length of the pad 72. This protruberance 73 constitutesa diaphragm and the pad 72 constitutes an integral support for thediaphragm. The interior of the protruberance 73 forms a chamber 74. Asillustrated the protruberance 73, and thus the chamber 74, taperstowards one end. A fuel inlet 75 opens into the larger end of thechamber 74 and a fuel outlet 76 opens from the narrower end of thechamber. The inlet 75 and outlet 76 extend from the outer surface of thepad 72 for connection to the inlet boss 62 and outlet boss 65respectively. The protruberance 73 may be untapered if desired. In somecircumstances it may be better for the protruberance 73, and thus thechamber 74, to taper from the fuel outlet end to the fuel inlet end ofthe pad, or to be un-tapered.

The pumps described are for use with single cylinder engines. They areprimarily intended for use on motorcycles, but they could possibly beused on other motor vehicles as well.

It will be understood that the pumps described may be adapted readilyfor use with multicylinder engines. For example for a two cylinderengine the first described pump illustrated by FIGS. 1 and 2 of theaccompanying drawings may be modified as shown in FIG. 7, so as toinclude two tubular members 28, instead of one, which are secured atangularly spaced positions adjacent the internal surface of theperipheral wall 11 of the housing so that as the disc oscillates whenthe eccentric 17 is rotated its periphery bears in turn on the tubularmembers 28 to compress their associated chambers. As before each tubularmember 28 has an inlet spigot 33 and an outlet spigot 34 connectedrespectively to a non-retum valve 37 and a normallyclosed pulse valve39. Alternatively the pump may be modified as shown in FIG. 8. In thisfurther modified form there are again two tubular members 28 but theyare secured side-by-side to the internal surface of the peripheral wall11 of the housing 10, and there are two similar discs 24 which aremounted on separate eccentries 17 carried by the shaft portion 16 andare restrained, as before, from rotation with the eccentrics 17 by acommon block 26. There is one tubular member 28 positioned opposite theperiphery of each disc 24 so that as the disc oscillates it bears on thetubular member to compress the associated chamber. The discs are soarranged that when the chamber of one tubular member 28 is beingcompressed the chamber of the other tubular member is uncompressed.

It has been found that numerous advantages may be obtained fromapparatus in accordance with the present invention when used as a pumpfor fuel injection. For example extremely accurate metering of fuel ispossible with resultant consistency in output and efficiency. Alsoefficient air/fuel mixing can be achieved with consequent economicaladvantages, and high performance can be obtained from engines with whichthe pump is used, and high torque with low r.p.m. Furthermore, engineswith which such a pump has been used have been found to give a veryclean exhaust.

It will be understood that apparatus of the form described above andillustrated in the accompanying drawings could be readily modified toconvert them for use as motors.

What is claimed is:

1. Apparatus capable of use as a pump or as a motor comprising:

a housing having a cylindrical inner surface;

a rotary shaft journalled in said housing axially of said inner surface;

eccentric means rotatable with said shaft;

a cylindrical compression member mounted'on said eccentric means withinsaid housing;

restraining means secured to said housing and engaged with saidcompression member to prevent said member from rotating with saideccentric means but to allow said compression member, by the rotaryaction of said eccentric means, to oscillate relative to the rotationalaxis of said shaft;

a closed-ended tubular member having a flexible supporting part and aflexible diaphragm of thinner section than said supporting part, whichsaid supporting part and diaphragm together define an arcuate closedfluid-receiving chamber which extends through an arc of substantiallyless than 360, said supporting part having a fluid entry therein whichopens into said chamber radially through said supporting part at one endthereof and a fluid outlet which opens into said chamber radiallythrough said supporting part at the opposite end thereof, and saidtubular member being mounted by said supporting part on said innersurface circumferentially thereof and directly opposite the periphery ofsaid compression member with said chamber extending arcuately adjacentpart of the periphery of said compression member and said diaphragmbeing towards, and lying on a circle centered on, the rotational axis ofsaid rotary shaft, said circle being of a diameter substantially equalto the diameter of said compression member;

and a normally closed pulse valve at said fluid outlet adapted to openwhen subjected to fluid pressure above a predetermined value,

the construction and arrangement being such that in use as saidcompression member oscillates its periphery bears intermittently on saiddiaphragm and urges said diaphragm resiliently towards said supportingpart to cause said chamber to be compressed progressively from saidfluid entry to said fluid outlet, and thereby to cause the pressure offluid in said chamber to be increased to a level which opens said pulsevalve and the fluid flows under pressure out of said chamber, and suchthat during each cycle of oscillating motion of said compression memberthere is a phase in which said chamber is not compressed by said memberand said pulse valve is closed, the flow of fluid out of said chamber inconsequence being intermittent and pulse-like.

2. Apparatus according to claim 1 wherein said tubular member comprisesan arcuate pad of flexible material which forms said supporting part andis provided with said fluid entry inlet and outlet, and on an innercircumferential surface of said pad a thin-walled, hollow protruberancewhich extends along a substantial part of the length of said innercircumferential surface and which forms said diaphragm, the interior ofsaid protruberance forming said chamber.

3. Apparatus according to claim 11 wherein said tubular member comprisesan annular pad of flexible material which forms said supporting part andis provided with said fluid entry inlet and outlet, and on an innercircumferential surface of said pad a thin-walled, hollow protruberancewhich extends along said inner circumferential surface and which formssaid diaphragm, the interior of said protruberance forming said chamber.

4. Apparatus according to claim 1 wherein said diaphragm, and hence saidchamber, tapers towards one end.

5. Apparatus according to claim 1 wherein there is a plurality of saiddiaphragms, and hence a plurality of said chambers, disposed atangularly spaced intervals around said compression member which as itoscillates bears in turn on said diaphragms to compress their associatedchambers.

6. Apparatus according to claim 1 wherein there is a plurality of saiddiaphragms, and hence a plurality of said chambers, and a plurality ofsaid compression members, there being at least one of said diaphragmspositioned adjacent the periphery of each said compression member.

7. Apparatus capable of use as a pump or as a motor comprising:

a housing having a cylindrical inner surface;

a rotary shaft journalled in said housing axially of said inner surface;

eccentric means rotatable with said shaft;

a cylindrical compression member mounted on said eccentric means withinsaid housing;

restraining means secured to said housing and engaged with saidcompression member to prevent said member from rotating with saideccentric means but to allow said compression member, by the rotaryaction of said eccentric means, to oscil late relative to the rotationalaxis of said shaft;

a closed-ended tubular member having a flexible supporting part and aflexible diaphragm of thinner section than said supporting part, whichsaid supporting part and diaphragm together define an arcuate, closedfluid-receiving chamber which extends through an arc of substantiallyless than 360, said supporting part having a fluid entry therein whichopens into said chamber radially through said supporting part at one endthereof and a fluid outlet which opens into said chamber radiallythrough said supporting part at the opposite end thereof;

a normally closed pulse valve at said fluid outlet adapted to open whensubjected to fluid pressure above a predetermined value;

a movable member mounted in said housing opposite the periphery of saidcompression member for movement towards and away from the rotationalaxis of said rotary shaft, which said movable member forms part of saidinner surface and on which said movable member said tubular member ismounted by said supporting part directly opposite the periphery of saidcompression member, with said chamber extending arcuately adjacent artof eri her 0 said 0 m ressi mber rid said cii phr gm bei ng tow r s, anl yiiig on a circle centred on, the rotational axis of said rotaryshaft, said circle being of a diameter substantially equal to thediameter of said compression member,

and means for moving said movable member towards and away from therotational axis of said rotary shaft thereby to cause said tubularmember to be moved towards and away from said compression member, theconstruction and arrangement being such that in use as said compressionmember oscillates its periphery bears intermittently on said diaphragmand urges said diaphragm resiliently towards said supporting part tocause said chamber to be compressed progressively from said fluid entryto said fluid outlet, and thereby to cause the pressure of fluid in saidchamber to be increased to a level which opens said pulse valve and thefluid flows under pressure out of said chamber, and such that duringeach cycle of oscillatory motion of said compression member there is aphase in which said chamber is not compressed by said member and saidpulse valve is closed, the flow of liquid out of said chamber inconsequence being intermittent and pulse-like, the extent by which saidchamber is compressed being adjustable by varying the position of saidmovable member, and thus of said tubular member, relative to therotational axis of said rotary shaft.

8. Apparatus according to claim 7 wherein said movable member is anarcuate shoe pivoted to said housing adjacent one end of said shoe forangular movement towards and away from said rotational axis of saidrotary shaft, and said means for moving said movable member comprising acam engageable with said movable member.

9. Apparatus according to claim 7 wherein said movable member is anarcuate shoe having integral therewith parallel tubular bosses, andwherein fixed parallel pegs are engaged in said bosses, and said bossesare slidable along said pegs such that said movable member can be movedlinearly towards and away from said rotational axis of said rotaryshaft.

1. Apparatus capable of use as a pump or as a motor comprising: ahousing having a cylindrical inner surface; a rotary shaft journalled insaid housing axially of said inner surface; eccentric means rotatablewith said shaft; a cylindrical compression member mounted on saideccentric means within said housing; restraining means secured to saidhousing and engaged with said compression member to prevent said memberfrom rotating with said eccentric means but to allow said compressionmember, by the rotary action of said eccentric means, to oscillaterelative to the rotational axis of said shaft; a closed-ended tubularmember having a flexible supporting part and a flexible diaphragm ofthinner section than said supporting part, which said supporting partand diaphragm together define an arcuate closed fluid-receiving chamberwhich extends through an arc of substantially less than 360*, saidsupporting part having a fluid entry therein which opens into saidchamber radially through said supporting part at one end thereof and afluid outlet which opens into said chamber radially through saidsupporting part at the opposite end thereof, and said tubular memberbeing mounted by said supporting part on said inner surfacecircumferentially thereof and directly opposite the periphery of saidcompression member with said chamber extending arcuately adjacent partof the periphery of said compression member and said diaphragm beingtowards, and lying on a circle centered on, the rotational axis of saidrotary shaft, said circle being of a diameter substantially equal to thediameter of said compression member; and a normally closed pulse valveat said fluid outlet adapted to open when subjected to fluid pressureabove a predetermined value, the construction and arrangement being suchthat in use as said compression member oscillates its periphery bearsintermittently on said diaphragm and urges said diaphragm resilientlytowards said supporting part to cause said chamber to be compressedprogressively from said fluid entry to said fluid outlet, and thereby tocause the pressure of fluid in said chamber to be increased to a levelwhich opens said pulse valve and the fluid flows under pressure out ofsaid chamber, and such that during each cycle of oscillating motion ofsaid compression member there is a phase in which said chamber is notcompressed by said member and said pulse valve is closed, the flow offluid out of said chamber in consequence being intermittent andpulse-like.
 2. Apparatus according to claim 1 wherein said tubularmember comprises an arcuate pad of flexible material which forms saidsupporting part and is provided with said fluid entry and outlet, and onan inner circumferential surface of said pad a thin-walled, hollowprotruberance which extends along a substantial part of the length ofsaid inner circumferential surface and which forms said diaphragm, theinteRior of said protruberance forming said chamber.
 3. Apparatusaccording to claim 1 wherein said tubular member comprises an annularpad of flexible material which forms said supporting part and isprovided with said fluid entry and outlet, and on an innercircumferential surface of said pad a thin-walled, hollow protruberancewhich extends along said inner circumferential surface and which formssaid diaphragm, the interior of said protruberance forming said chamber.4. Apparatus according to claim 1 wherein said diaphragm, and hence saidchamber, tapers towards one end.
 5. Apparatus according to claim 1wherein there is a plurality of said diaphragms, and hence a pluralityof said chambers, disposed at angularly spaced intervals around saidcompression member which as it oscillates bears in turn on saiddiaphragms to compress their associated chambers.
 6. Apparatus accordingto claim 1 wherein there is a plurality of said diaphragms, and hence aplurality of said chambers, and a plurality of said compression members,there being at least one of said diaphragms positioned adjacent theperiphery of each said compression member.
 7. Apparatus capable of useas a pump or as a motor comprising: a housing having a cylindrical innersurface; a rotary shaft journalled in said housing axially of said innersurface; eccentric means rotatable with said shaft; a cylindricalcompression member mounted on said eccentric means within said housing;restraining means secured to said housing and engaged with saidcompression member to prevent said member from rotating with saideccentric means but to allow said compression member, by the rotaryaction of said eccentric means, to oscillate relative to the rotationalaxis of said shaft; a closed-ended tubular member having a flexiblesupporting part and a flexible diaphragm of thinner section than saidsupporting part, which said supporting part and diaphragm togetherdefine an arcuate, closed fluid-receiving chamber which extends throughan arc of substantially less than 360*, said supporting part having afluid entry therein which opens into said chamber radially through saidsupporting part at one end thereof and a fluid outlet which opens intosaid chamber radially through said supporting part at the opposite endthereof; a normally closed pulse valve at said fluid outlet adapted toopen when subjected to fluid pressure above a predetermined value; amovable member mounted in said housing opposite the periphery of saidcompression member for movement towards and away from the rotationalaxis of said rotary shaft, which said movable member forms part of saidinner surface and on which said movable member said tubular member ismounted by said supporting part directly opposite the periphery of saidcompression member, with said chamber extending arcuately adjacent partof the periphery of said compression member and said diaphragm beingtowards, and lying on a circle centred on, the rotational axis of saidrotary shaft, said circle being of a diameter substantially equal to thediameter of said compression member, and means for moving said movablemember towards and away from the rotational axis of said rotary shaftthereby to cause said tubular member to be moved towards and away fromsaid compression member, the construction and arrangement being suchthat in use as said compression member oscillates its periphery bearsintermittently on said diaphragm and urges said diaphragm resilientlytowards said supporting part to cause said chamber to be compressedprogressively from said fluid entry to said fluid outlet, and thereby tocause the pressure of fluid in said chamber to be increased to a levelwhich opens said pulse valve and the fluid flows under pressure out ofsaid chamber, and such that during each cycle of oscillatory motion ofsaid compression member there is a phase in which said chamber is notcompressed by said member and said pulse valve is closed, the flow ofliquid out of said chamber in consequence being intermittent andpulse-like, the extent by which said chamber is compressed beingadjustable by varying the position of said movable member, and thus ofsaid tubular member, relative to the rotational axis of said rotaryshaft.
 8. Apparatus according to claim 7 wherein said movable member isan arcuate shoe pivoted to said housing adjacent one end of said shoefor angular movement towards and away from said rotational axis of saidrotary shaft, and said means for moving said movable member comprising acam engageable with said movable member.
 9. Apparatus according to claim7 wherein said movable member is an arcuate shoe having integraltherewith parallel tubular bosses, and wherein fixed parallel pegs areengaged in said bosses, and said bosses are slidable along said pegssuch that said movable member can be moved linearly towards and awayfrom said rotational axis of said rotary shaft.